This proposal describes a study of fluid-structure interaction phenomena within the human larynx during phonation. The motion of the vocal folds is driven in part by the aerodynamic pressure on their surfaces. During phonation, there is a periodic exchange of energy between the elastic deformation of the vocal folds and the surface pressures associated with the airflow through the larynx. A good understanding of the associated fluid-structure interaction mechanisms is of utmost importance in order to develop accurate predictive models of phonatory processes, and accurate estimates of the stresses within the tissue. The purpose of the proposed research is to gain a thorough understanding of the mechanics of fluid-induced oscillations of the laryngeal tissue, including aspects related to the possible role of the false vocal folds in phonation. The aims are to: 1) perform detailed flow, kinematic, and sound measurements using a self oscillating physical model of the larynx and the false vocal folds; 2) develop detailed and accurate computational models as well as approximate reduced order models for the prediction of fluid flow, radiated sound, and tissue deformation of the larynx and false folds; and 3) determine the effects on laryngeal dynamics of normal and pathological conditions of the larynx, and clarify the role of the false vocal folds. Fundamental phonation processes will be isolated and studied. The different theoretical and physical models will be used to cross-validate new information that bridges from idealized models and real larynx phonation. Comparisons will be made between data obtained using the physical models and the numerical predictions. This will allow the validation of the numerical models, and reinforce our understanding of the physical phenomena involved. The overarching goal is to develop accurate computer prediction models of voice production that may eventually be useful for making precise diagnostic decisions in the voice clinic, targeting optimal intervention strategies for voice problems, and achieving high quality articulatory speech synthesis. Accurate stress calculations are also needed and useful for tissue damage predictions. This research program is a collaboration among laboratories at Bowling Green State University and Purdue University.